1. Field of the Invention
The present invention relates to a device for measuring the heading error or a missile, comprising a focusing lens, an array of detectors placed in the focal plane of the lens, a device for sequentially analyzing the field of observation, a processing device adapted for delivering, from the signal supplied by the detectors, signals representative of the coordinates of the missile.
2. Description of the Prior Art
In practice, the focusing lens and the device for analyzing the field of observation are integrated in an optronic box. This box receives the infrared radiation emitted for example by the pyrotechnic tracers fixed to the rear of the missile and focuses it on the detectors. The device for analyzing the field of observation is formed by an opto-mechanical system generally comprising at least two prisms, as will be seen further on, rotated mechanically for driving the image of the instantaneous field of the device, and the missiel-source with it, in relative circular translation with respect to the detectors and thus cause scanning thereof by the missile-source. As for the processing device or case, from a time reference, it allows the passage times of the missile over the detecting means during scanning thereof to be calculated, the angular then metric measurement of the heading error of the missile with respect to a siting axis to be determined and different anti-decoy treatments to be effected. The measurement of the heading error of the missile is then transmitted to an electronic guidance circuit which deduces therefrom the corrections to be made to the steering controls of the missile for bringing it back to the siting line.
It should be noted here that the invention applies to heading error measurement devices of the cruciform type and, more generally to heading error measurement devices with sampling or sequential scanning.
The infrared heading error measurement devices used for guiding missiles require at least two, even three fields of observation with as many optical and detection systems, namely a large field on firing for taking charge (PC) and rapid acquisition of the missiles, an intermediate field, not always used it is true, for guiding during the first part of the trajectory and a small field, called cruising field (CR), for accurate guiding of the missiles until they impact on the target.
In these heading error measurement devices, and only considering the PC and CR fields, the equipment is therefore doubled: two detector arrays, sometimes two cryostats and two preamplifier chains; often two mechanisms for rotating the scanning prisms, respectively for the PC channel and the CR channel which raises a problem of synchronization between these two channels, resolved up to now by using two sets of gears, but to the detriment of the accuracy.
Furthermore, an electric circuit must be provided for switching the data relative to the PC-CR fields.
These are drawbacks which the present invention aims at eliminating.
To resolve his problem, the applicant has taken as basis the fact that, for example in a heading error measuring device with filiform detectors disposed in a cross, split up or not, with one cross or two crosses, for improving the anti-decoy characteristic, the detectors are used for only a part of the time.